Good thread, but hard to compare the two.
He was a lot more lithe and agile back then - before the back break - and played with unpredictable abandon. He had link up play, but only with Martial. He ran blind alleys and didn't have the best decision making, or better to say everything was more self-absorbed - if his plays worked out, they looked fantastic, but when they didn't, his choice of action could fairly be questioned as there'd mostly be a 'better' option he could have selected. At the clip he was scoring and affecting games, it didn't matter much because it looked like he was on a trajectory towards superstardom, regardless.
The current version is more efficient, more considered, stronger and a whole lot more spatially aware. He's benefiting from being coached and it shows in his actions going from play to play, for the most part. This more mature Rashford is on the verge if transitioning, too. A pseudo striker/wide forward mirroring Henry looks very much on the cards if the current trajectory continues unabated.
I think, for dependability's sake, you'd have to take the current version because he's reliable and more ready to lead an entire attacking line, if not with goals, then knowing how to affect the game to the benefit of others.